UNIVERSITY  OF  ILLINOIS 

Agricultural  Experiment  Station 


BULLETIN  No.  314 


A  TECHNICAL  STUDY 

OF  THE  MAINTENANCE  AND 

FATTENING  OF  LAMBS 

AND  THEIR  UTILIZATION  OF  A  RATION 
OF  ALFALFA  HAY  AND  CORN 

BY  H.  H.  MITCHELL,  W.  G.  KAMMLADE, 
AND  T.  S.  HAMILTON 


URBAXA,  ILLINOIS,  AUGUST,  1928 


CONTENTS 

PACE 

PLAN  OF  THE  EXPERIMENT 31 

CHEMICAL  COMPOSITION  OF  CHECK  LAMBS 33 

MAINTENANCE  EXPERIMENT 37 

Body  Weight  Changes 38 

Results  of  Digestion  and  Metabolism  Trials 38 

Average  Daily  Intake  of  Feed  and  Energy 40 

Composition  of  the   Maintenance   Lambs 40 

Changes  in  Energy  Content  of  the  Maintenance  Lambs 44 

Corrected  Maintenance   Requirements 45 

Net  Energy  Required  for  Maintenance 47 

THE  FATTENING  EXPERIMENT 48 

Results  of  the  Digestion  and  Metabolism  Trials 50 

Composition  of  the  Fat  Lambs 51 

Composition  of  the  Gains  in  Weight 54 

Distribution  of  Added  Nutrients  in  the  Carcasses 56 

Utilization  of  Feed  Energy  in  Fattening 57 

SUMMARY 59 


A  TECHNICAL  STUDY  OF  THE  MAINTENANCE 

AND  FATTENING  OF  LAMBS  AND  THEIR 

UTILIZATION    OF    A    RATION    OF 

ALFALFA  HAY  AND  CORN 

H.  H.  MITCHELL,  W.  G.  KAMMLADE,  AND  T.  S.  HAMILTON1 

The  lack  of  information  concerning  the  nutrient  requirements  of 
sheep  and  their  efficiency  in  utilizing  food  nutrients,  is  mainly  responsi- 
ble for  the  general  application  to  sheep  of  results  obtained  with  cattle, 
and  for  the  complacency  felt  in  thus  transferring  bodily  to  one  species 
information  and  measurements  secured  with  another.  It  is  high  time 
that  experimental  investigations  on  the  nutrition  of  sheep  be  carried 
out  that  will  either  establish  this  assumed  similarity  between  sheep 
and  cattle  or  will  permit  a  separate  evaluation  of  sheep. 

In  Bulletin  283  of  this  Station  is  a  description  of  an  experiment 
on  12  sheep  designed  to  determine  the  maintenance  requirement  in 
terms  of  metabolizable  energy,  the  composition  of  gains  put  on  during 
fattening,  and  the  relation  between  the  metabolizable  energy  consumed 
above  maintenance  and  the  gross  energy  of  the  gains  made.  The  ra- 
tions used  in  all  cases  consisted  of  alfalfa  hay  only.  The  rate  of  fat- 
tening secured  on  alfalfa  hay  alone  was  slow,  and  the  refusal  of  feed 
in  some  of  the  metabolism  trials  as  well  as  during  the  fattening  period 
complicated  the  interpretation  of  some  of  the  results  secured.  It  was 
therefore  decided  to  repeat  the  experiment  using  a  ration  more  accept- 
able to  sheep  and  more  conducive  to  fattening.  In  other  respects  also 
the  plan  of  the  second  experiment  differed  from  that  of  the  first  tho 
the  objects  sought  were  essentially  the  same. 

PLAN  OF  THE  EXPERIMENT 

The  general  plan  of  the  experiment  provided  for  the  slaughter  and 
analysis  of  a  group  of  check  lambs  at  the  beginning  of  the  experiment 
and  of  a  group  of  fattened  lambs  at  the  end  of  the  experiment.  From 
these  results  the  composition  of  the  gains  put  on  during  fattening  could 
be  computed.  A  third  group  of  lambs  was  to  be  fed  such  amounts  of 
the  fattening  ration  as  may  be  required  for  the  maintenance  of  weight, 
The  slaughter  and  analysis  of  these  lambs  at  the  end  of  their  mainten- 
ance feeding  either  would  demonstrate  that  the  ration  consumed  was 
in  fact  a  maintenance  ration  (with  respect  to  energy)  or  would  afford 


'H.   H.   Mitchell,  Chief  in  Animal   Nutrition;    W.   G.   Kammlade,   Assistant   Chief   in  Sheep 
Husbandry ;   and  T.  S.  Hamilton,  Associate  in  Animal  Nutrition. 

31 


32  BULLETIN  No.  314  [August, 

a  more  or  less  satisfactory'  basis  for  correcting  the  ration  fed  by  mak- 
ing due  allowance  for  energy  stored  in  or  lost  from  the  body  during 
the  feeding  period. 

It  was  decided  to  use  young  lambs  in  this  work  and  to  carry  the 
fattened  lambs  to  a  desirable  market  weight  of  approximately  90 
pounds.  In  the  spring  of  1925  the  required  number  of  grade  lambs, 
about  three  months  of  age  was  available,  and  accordingly  on  April  16 
six  of  these  lambs  were  killed  and  subsequently  analyzed.  These  were 
to  constitute  the  check  group.  The  ration  chosen  consisted  of  equal 
parts  of  alfalfa  hay  and  corn.  Two  other  groups  of  lambs  were  started 
on  maintenance  and  fattening  rations,  but  they  did  not  eat  well.  They 
did  not  adapt  themselves  to  the  system  of  individual  feeding,  probably 
because  they  were  too  young,  and  the  experiment  was  therefore  dis- 
continued. 

In  the  fall  of  the  same  year  some  lambs  were  obtained  from  an 
Oregon  ranch.  They  were  a  mixed  group  of  ewes  and  wethers,  dropped 
by  western  ewes  bred  to  purebred  Hampshire  rams.  At  the  time  the 
experiment  was  resumed  in  September,  they  were  from  five  to  five  and 
a  half  months  old.  On  September  21,  eight  of  these  lambs  were  slaugh- 
tered and  analyzed  as  a  check  group;  another  group  of  eight  was  fed 
a  ration  of  alfalfa  hay  and  corn  in  equal  parts  for  maintenance  of 
weight,  while  a  third  group  of  nine  was  fed  for  fattening  on  the  same 
ration.  The  lambs  were  fed  individually  in  all  cases. 

The  individual  feeding  of  these  lambs  was  successful.  The  main- 
tenance group  was  on  feed  until  the  early  part  of  February  or  March, 
the  final  date  varying  for  different  individuals.  During  this  period 
metabolism  and  digestion  trials  were  made  upon  each  of  the  eight 
lambs.  At  the  termination  of  the  period  of  experimental  feeding,  the 
lambs  were  slaughtered  and  analyzed. 

The  lambs  in  the  fattening  group  were  fed  until  weights  approxi- 
mating 90  pounds  were  reached,  when  they  were  slaughtered  and  ana- 
lyzed. Two  of  the  lambs  were  slaughtered  on  December  21,  1925,  five 
on  January  5,  1926,  one  on  February  9,  and  one  on  February  18.  Di- 
gestion and  metabolism  trials  were  made  upon  only  five  of  the  nine 
lambs  in  this  group. 

The  pen  in  which  the  lambs  were  allowed  to  exercise  was  approxi- 
mately one  by  five  rods.  The  lambs  were  fed  in  individual  feeding 
crates  located  in  a  shed  open  toward  the  south.  Water  and  salt  were 
provided  ad  libitum.  Except  at  feeding  time,  the  lambs  were  allowed 
the  run  of  the  open  pen.  Body  weights  were  taken  weekly,  and  all 
feed  used  was  sampled  continuously  and  submitted  to  a  routine  chem- 
ical analysis,  including  the  determination  of  calcium  and  of  the  heat 
of  combustion.  The  carcass  samples  also  were  analyzed  for  calcium 
and  gross  energy. 


THE  MAINTENANCE  AND  FATTENING  OF  LAMBS  33 

CHEMICAL  COMPOSITION  OF  CHECK  LAMBS 

Altho  the  results  of  the  analysis  of  the  first  group  of  check  lambs 
were  not  used  in  the  later  computations  of  the  experiment,  they  are 
nevertheless  reported  because  of  their  interest  and  importance  as  rep- 
resentative of  the  composition  of  lambs  three  to  four  months  of  age. 

Two  samples  were  prepared  from  each  lamb  for  chemical  analysis: 
ll)  a  carcass  sample  prepared  from  one-half  of  the  dressed  carcass, 
including  one  kidney;  and  (2)  an  offal  sample,  including  the  blood, 
head,  skin,  and  feet,  visceral  fats,  and  all  viscera  except  the  kidneys. 
A  composite  wool  sample  for  the  group  of  six  lambs  was  also  analyzed, 
the  lambs  being  shorn  before  slaughter.  In  preparing  the  two  samples 
the  different  tissues  were  ground  separately  according  to  convenience 
and  ultimately  mixed  together  thoroly. 

The  slaughter  data,  the  total  weights  of  lean,  fat,  bone,  offal,  and 
wool,  and  the  percentage  composition  of  the  chemical  samples  from 
the  first  group  of  grade  lambs  will  be  found  in  Tables  1,  2,  and  3.  The 
estimated  percentage  composition  and  gross  energy  content  of  the 
lambs,  on  the  basis  of  the  live  weight  as  well  as  of  the  empty  weight, 
are  given  in  Table  4. 

About  a  year  before  the  first  group  of  check  lambs  was  slaugh- 
tered, advantage  was  taken  of  an  opportunity  to  analyze  a  number  of 
new-born  lambs  that  had  died  from  unknown  causes  a  day  or  two 
after  birth.  Four  of  these  new-born  lambs  were  of  average  weight  or 
better  and  appeared  normal  in  every  respect.  The  first  two  were  pre- 
mature, having  been  dropped  about  ten  days  before  the  termination  of 
the  normal  gestation  period.  They  were  subnormal  in  weight  and 
composition.  Since  these  analyses  have  not  heretofore  been  published, 
they  have  been  summarized  in  Table  5.  They  possess  the  same  gen- 
eral significance  as  the  analysis  of  other  groups  of  lambs  reported  in 
this  bulletin. 

The  second  group  of  check  lambs,  used  in  the  computations  of 
this  experiment,  was  slaughtered  and  analyzed  according  to  the  same 
scheme  as  the  first  group,  the  samples  being  composited  in  exactly 
the  same  manner.  The  results  obtained  are  summarized  in  Tables  6. 
7,  8.  and  9. 

These  western  lambs  were  in  somewhat  poorer  condition  than  the 
younger  grade  lambs  killed  in  the  spring  of  1925.  Another  noticeable 
difference  between  the  western  and  the  grade  lambs  relates  to  the  ash 
content.  The  western  lambs  contained  4.79  percent  of  ash  on  the  basis 
of  the  empty  weight,  while  the  grades  contained  only  3.32  percent.  The 
calcium  made  up  approximately  the  same  percentage  of  the  total  ash 
in  each  group,  i.e.,  28.5  and  27.4.  The  greater  ash  content  of  the  west- 
ern lambs  may  be  traced  definitely  to  their  greater  bone  content.  No 
weights  on  the  total  skeleton  are  available,  but  the  bones  in  the  dressed 


34 


BULLETIN  No.  314 


[August, 


TABLE  1. — SLAUGHTER  DATA  FROM  FIRST  GROUP  OF  CHECK  LAMBS 

(All  weights  in  pounds) 


Lamb  No  

1 

21 

25 

12 

22 

30 

Average 

Live  weight  

47.4 

50.1 

47.8 

54.4 

50.9 

49.7 

50.1 

Wool  

1.76 

1.65 

1.08 

1.71 

1.54 

1.11 

1.48 

Blood  ... 

1.94 

2.19 

2.25 

2.19 

2.31 

2.38 

2.21 

Skin  and  feet  

4.44 

4.56 

4.56 

4.38 

5.13 

4.69 

4.63 

Caul  fat 

.56 

.56 

.50 

.56 

.19 

.44 

47 

Gut  fat           

.31 

.31 

.44 

.56 

.75 

.44 

.47 

Contents  of  first  three 

6.25 

4.63 

6.38 

6.06 

4.31 

4.69 

5.39 

Contents  of  4th  stomach 

2.44 

2.06 

2.13 

1.38 

1.75 

1.31 

1.85 

Contents  of  entire 

8.69 

6  69 

8  51 

7.44 

6.06 

6.00 

7.23 

Warm  dressed  carcass.  .  . 
Cold  dressed  carcass  

20.81 
20.05 
3.65 

25.38 
24.85 
2  09 

21.06 
20.90 
76 

27.31 
26.53 
2  86 

24.50 
23.50 
4.08 

24.25 
23.50 
3.09 

23.89 
23.22 

2.76 

18.3 

13.3 

17.8 

13.6 

11.9 

12.1 

14.5 

Dressing  percentage  

42.7 

49.6 

43.8 

48.8 

46.2 

47.2 

46.4 

TABLE  2. — WEIGHTS  OF  SAMPLES  ANALYZED  FROM  FIRST  GROUP  OF  CHECK  LAMBS 


Lamb 
No. 

Empty 
weight 

Dressed  carcass  composite 

Offal 

Wool 

Lean 

Fat 

Bone 

Total 

1 

kgs. 
17.58 
19.69 
17.81 
21.30 
20.35 
19.84 

19.43 

grams 
5  988 
7  352 
6  035 
7  672 
6  876 
6  748 

6  779 

grams 
1  391 
2  035 
1  432 
2  286 
1  706 
2  Oil 

1  810 

grams 
1  736 
1  722 
1  783 
1  998 
2  028 
1  808 

1  846 

grams 
9   115 
11   109 
9  250 
11  956 
10  610 
10  567 

10  435 

grams 
6  740 
6  730 
7  140 
7  161 
7  561 
7  224 

7  093 

grams 
798 
748 
490 
776 
699 
503 

669 

21  

25  

12 

22  

30  

Average..  . 

TABLE  3. — PERCENTAGE  COMPOSITION  AND  ENERGY  VALUE  OF  SAMPLES 
ANALYZED  FROM  FIRST  GROUP  OF  CHECK  LAMBS 


Lamb 
No. 

Dry 
substance 

Crude 
protein 

Ether 
extract 

Ash 

Calcium 

Calcium 
in  percent 
of  total 
ash 

Gross 
energy 
per  grams 

Carcass  composite  samples 


1  

44.04 

17.11 

21.23 

5.21 

1.85 

35.5 

sm.  cals. 
2  866 

21   

48.32 

16.32 

24  77 

4  62 

1  46 

31.6 

3  088 

25  

43.47 

18.26 

19  62 

5  22 

1.72 

33.0 

2  746 

12 

53.56 

15  95 

26  74 

3  55 

99 

27.9 

3  306 

22  

44.02 

16.87 

22   15 

3  90 

1.28 

32.8 

2  897 

30 

44  74 

16  46 

23  32 

3  55 

1  01 

28  5 

2  951 

Average.  .  .  . 

46.36 

16.83 

22.97 

4.34 

1.39 

31.6 

2  976 

Offal  samples 


1... 

32  .  08 

16  89 

12  10 

2  47 

59 

23  9 

1  969 

21  

34.31 

16.88 

12  79 

1  85 

47 

25  4 

2  086 

25  

29.76 

17  07 

9  93 

2  10 

48 

22  9 

1  780 

12  

32.70 

16  06 

12  22 

1  83 

40 

21  9 

2  112 

22  . 

28.93 

16  37 

0  52 

1  89 

39 

20  6 

1  760 

30  

28.94 

16  44 

9  58 

1  94 

41 

21.1 

1  743 

Average  

31.12 

16.62 

11.02 

2.01 

.46 

23.5 

1  908 

Composite  wool  samples 


1-30...        91.89 

70.75 

13.75 

7  47 

.28 

3.75 

4  938 

1928] 


THE  MAINTENANCE  AND  FATTENING  OF  LAMBS 


35 


TABLE  4. — PERCENTAGE  COMPOSITION  AND  GROSS  ENERGY  CONTENT 
OF  FIRST  GROUP  OF  CHECK  LAMBS 


Lamb 
No. 

Dry 
substance 

Crude 
protein 

Crude 
fat 

Ash 

Calcium 

Calcium 
in  percent 
of  total 
ash 

Gross 
energy 
per  gram 

On  basis  of  live  weight 


1 

32   11 

15  15 

13  29 

3  25 

98 

sm.  cals. 
2  013 

21 

36  80 

15  32 

16  37 

3  08 

86 

2  290 

25  

30.46 

15.00 

11.95 

3.09 

.  90 

1  870 

12 

38  33 

14  63 

16  94 

2  47 

80 

2  370 

22  

32  47 

15  24 

13  72 

2  64 

72 

2  059 

30  

32.27 

14..  54 

14.32 

2  44 

.61 

2  050 

Average.  .  .  . 

33.74 

14.98 

14.43 

2.83 

.78 

2  109 

On  basis  of  empty  weight 


1.  .. 

39  30 

IS  54 

16  27 

3  98 

1  20 

30  2 

2  465 

21  

42.46 

17.67 

18.82 

3.56 

1.00 

28  1 

2  643 

25 

37  06 

IS  25 

14  54 

3  76 

1  09 

29  0 

2  276 

12  

44.41 

16  95 

19  63 

2  SB 

70 

24.5 

2  746 

22  

36.86 

17.30 

15  58 

3.00 

,82 

27.3 

2  338 

30 

36  69 

16  53 

16  28 

2  77 

70 

25  3 

2  331 

Average.  .  .  . 

39.46 

17.54 

16.85 

3.32 

.92 

27.4 

2  467 

TABLE  5. — PERCENTAGE  COMPOSITION  AND  GROSS  ENERGY  OF  XEW-BORN  LAMBS 


Breeding 

Birth 
weight  l 

Dry 
substance 

Crude 

protein 

Ether 
extract 

Ash 

Gross 
energy  per 
grams 

Ibs. 
6  0 

18  99 

11  38 

2  32 

2  35 

sm.  cals. 
1  Oil 

7  0 

18  04 

11   19 

1   SI 

•'   (is 

882 

9  75 

23  02 

14  94 

2  S2 

3  36 

1    148 

10  7 

23  32 

15  44 

2   SS 

3  02 

1   30S 

Southdown  

6  6 

24  69 

15  19 

2   76 

3  S4 

1  324 

Southdown  

7.2 

22  66 

16  44 

2  44 

3.35 

1  236 

Average2 

23.42 

15.50 

2.72 

3.39 

1  254 

'Sixteen  Southdown  lambs  dropped  from  ewes  in  the  University  flock  during  the  same  year 
averaged  7.7  pounds  in  weight  at  birth;  24  Rambouillet  lambs  averaged  9.7  pounds.  Exclusive  of 
first  two  lambs. 


TABLE  6. — SLAUGHTER  DATA  FROM  SECOND  GROUP  OF  CHECK  LAMBS 

(All  weights  in  pounds) 


Lamb  Xo 

156 

29 

64 

44 

83 

7> 

80 

81 

Aver- 

age 

Live  weight  

59  7 

60  6 

5s  4 

60  6 

57  4 

5S    1 

• 

58  6 

Wool 

3  38 

3  38 

2  81 

3  06 

3  69 

•'   ti3 

3   13 

3   13 

3   15 

Blood  

3  44 

2  81 

2  63 

2  25 

2  7.") 

3  00 

2  r:> 

2  63 

2  7s 

Skin  and  feet  

6  38 

4  75 

5  38 

4    SI 

5  (ID 

- 

5   19 

5.38 

5.34 

Caul  fat    . 

25 

69 

3s 

81 

44 

."id 

56 

38 

.50 

Gut  fat  

56 

44 

56 

50 

44 

44 

44 

44 

.48 

Contents  of  first  tin 

5  19 

6  81 

4  81 

5  31 

9  81 

6  56 

6  06 

5.69 

6.28 

Contents  of  4th  stomach 

4  31 

3   13 

3  06 

2  50 

3  56 

2  88 

2  69 

2  44 

3.07 

Contents  of  entire 
alimentary  tract  
Warm  dressed  carcass.  . 
Cold  dressed  carcass  .... 
Percent  shrinkage  
Percent  "fill" 

9.50 
26.19 
25.61 
2.21 
15  9 

9.94 
28.19 
27.60 
2.09 
16  4 

7.87 
27.94 
27.20 
2.65 
13  7 

7.81 
27.56 
26.86 
2.64 
13  3 

13.37 
26.25 
25.49 
2.90 

22    1 

9.44 
26.38 
25.68 
2  ..65 

16   4 

8.75 

27  .  :>!> 
26.66 
3.27 
15   1 

8.13 
8 
! 
3.28 

14.6 

9.35 
26.99 
26.27 
2.70 
15.9 

Dressing  percentage.  .  .  . 

42.9 

45.6 

47.3 

46.0 

42.1 

44.8 

45.9 

44.9 

36 


BULLETIN  Xo.  314 


I 


ss  .i;ed  1.846  grams  for  the  grades  and  2.588  grams  for  the 

western  lambs,  which  is  equal  to  9.52  and  11.61  percent  respectively 
the  empty  weight  and  11.45  and  13.52  percent  of  the  fat-free  empty 
weight. 


TABLE  7. — WEIGHTS  OF  SAMPLES  ANALYZED  FROM  SECOND  GROUP  OF  CHECK  LAMBS 


Lamb 

;•. 

Empty 

Dressed      -     •-         -    • 

-'• 

Wool 

:.'. 

Fat 

Bone1 

!'  •' 

ii 

1 

22   -- 
22.  97 
22    : 
22      7 
21.41 
21.75 
22.4 
21.  ( 

22.30 

- 
'  413 

1    •-; 

.     .  ,- 

]  L7 

-   B  •- 
•    ' 
r  896 

:    _  K 

'  616 

- 

:         92 

1  441 
' 
". 
1   133 
1   130 
1  211 
1  000 

1  349 

• 

-   858 
2   •     • 
. 
2  641 
2  523 
2    < 
2  646 
2  543 

.    588 

11  453 
12  047 

9 
'      78  I 
11  3.50 
•    2     • 
11  7i 
10   342 

11   553 

- 

-    852 
- 
7    571 
"  617 
7     ;- 
7    •   7 
- 
7  886 

-      .  ' 

1  .533 
1  533 
1   27i 

;  388 

1  674 
1   193 
1  420 

1     •  -• 

1  430 

•  . 

44 

S3   ...      . 

-- 

- 

51 

'     :  -  ...- 

Exclus          f  I  ies  of  1       I  and  feel 


TABLE  S. — PERCENTAGE  C<  -      fa  <  ION  AND  ENERGY  VALUE  OF  SAMPLES 
ANALYZED  FROM  SECOND  GROUP  OF  CHECK  LAMBS 


Lamb 

, 

- 

pro- 

:  •    - 
- 

Calcium 

in  percent 

•    . 

C 

per  trr 

•mposite  san.: 

156..  .. 

• 

' 
-      •  - 
Z 
- 
- 
- 
ti 
.. 

• 

17 

17   1 
7 

17.31 

-    -  - 
• 
• 

-      ~ 

; 
_     -  - 
- 
-     - 
• 
•  - 

7    - 
7    1 

- 

-    ; 
' 

1     ! 

4.77 

- 
•- 
5.90 

5.90 

.-    '  1 
- 
• 
_ 
1.56 
_ 
• 
•_ 

1.99 

1    ~ 

1   2 
34.4 
-     J 

• 
- 
• 

3.3  .  7 

caii. 

2      - 

'    - 

_ 
^ 
-    177 

^ 

2  691 

\ 

- 

• 

• 

Offal  samples 

156 

27     7 

i 
i 

30.26 

- 
- 

• 
- 
16.44 

7.32 
12.63 

13.15 
9.60 

11.14 

9.91 

10.36 

i  ii 

• 

ii  . 

.71 

_ 

88 
77 
- 
.71 

K 

23.1 

.         ! 

2 
24.6 
- 
25.0 

24.5 

J7 

2  005 

1   701 
2 
- 
1   77- 
1   914 
1   71- 

• 

. 

- 

- 
78 

- 
- 

Composite  wool  sample 

Entire  group 

91.57 

70.19 

6.47 

10.88 

.28 

2.57 

4  563 

:     - 


THE  MAINTENANCE  AND  FATTE> 


- 


TABLE  9. — PERCENTAGE  COMPOSITION  AND  Gr;< .•--  I       :  NTENT 

OF  SECOND  GROCP  OF  CHECK  LAMBS 


Lamb                  Dry                 Crude                         : 

Xo.             substance          pr-  .  •                      :ract 

Ui 

- 
- 
• 
ri 

Gross 

'- 
•  sram 

1  .       M     •  .         reigfat 

156       .                   31  66 

16.66 
16.42               12     12 
•       -               13.04 
LS.84               14.75 
16  .  02               10.95 
11.37 
17.06               11.41 
16.96 

16.40               11.90 

4.73 
32 

3.45 
4.34 
3.49 

;   21 
; 
3.99 

-     2 

1.32 

1 

.    _ 
_ 
2 
- 
.01 

1.14 

',  ','.',  .'  ','•', 

/  i  -  o;  *.  to 

co2s. 

i      •  \ 
.      17 
-   -   • 
I  851 

1  909 
1 

:   a  •- 

1    171 

29  ...                 34  73 

64  33.74 

44                          35  OS 

83             .             30  9>, 

78  ...      .             32  54 

80                          ?.3  33 

81   .                        •••-•, 

Average  33.09 

•       _  .    |    •   -  •  -         gfai 

156  37.64 

19.81               11.51 
19.64 
L8.7S              15.10 
18  .  29               L7  .  02 

14.11 
19.17               13.61 
20.09               13.44 

1      -•                  _      • 

19.52               14.15 

!   •  - 
1    S7 
1 
' 
1    18 
' 
-    9S 
1   -  - 

4.79 

:   ^ 
- 
1.45 
>7 
1.43 
3 
18 

1.36 

2   1    1 
2    V  ' 
_      ' 
2  581 
.      -' 
_    284 
2  274 
2  2li 

2  346 

29  41.54 

64                          39  09 

44.                           10.49 

83  " 

78..                       5.8J 

39  24 

81  S.24 

Average  39.37 

MAINTENANCE  EXPERIMENT 

The  feeding  of  the  eight  maintenance  lambs  started  on  October 
10.  1925.    Their  weekly  weight.-  from  this  ".mil  February  6  or  13 

are  given  in  Table  10. 


TABLE  10. — WEEKLY  WEIGHTS  OF  LAMBS  DURING  MAINTENANCE  FEEDING  PERIOD* 

-    '   :          ~ 


Lamb  Xo 

10 

11 

- 

. 

- 

136 

_ 

Oct.  10 

65 

63 

65 

• 

- 

63 

i 

17 

. 

- 

' 

i 

61 

61 

24 

] 

j 

66 

65 

- 

31 

64 

65 

65 

fifi 

65 

_ 

Nov.  7 

72 

69 

' 

69 

1 

- 

J 

14 

- 

69 

66 

64 

- 

21 

69 

~ 

71 

~ 

69 

28 

67 

- 

70 

69 

66 

64 

Dec.  5 

- 

66 

J 

71 

1 

i 

69 

12 

1 

J 

' 

- 

- 

19 

66 

65 

• 

a 

66 

66 

- 

- 

69 

- 

-_ 

71 

• 

n 

- 

Jan   - 

' 

70 

73 

i 

74 

70 

73 

9 

70 

- 

n 

- 

j  | 

69 

16 

69 

71 

-- 

j 

-I 

- 

- 

23 

71 

74 

- 

74 

73 

- 

30 

71 

73 

J 

' 

73 

- 

Feb.  6 

73 

79 

77 

:: 

n 

1 

-  . 

13 

76 

-' 

Final  weight  .... 

69.4 

73.2 

71.7 

71.6 

74.9 

69.0 

n  i 

'-  - 

Average  weight  . 

68.2 

69.2 

70.6 

J 

69.3 

67.1 

70.6 

66.5 

'Xo.    136  was  slaughtered  on  Fei>:  .   • -.     »     N :    -     :       . .     .       "  -  »     and 

Xos.    11   and   43  on   March   4.     Some  of  the  weekly  w,  j  ;1   from 

the  table  and  from  the  averages  because  of  irregularities  incide:.' 


38  BULLETIN  Xo.  314  [August, 

Body  Weight  Changes 

The  weight  records  in  Table  10  indicate  that  the  feeding  was  ap- 
preciably more  liberal  than  a  maintenance  ration.  All  lambs  increased 
in  weight  slowly.  They  were  started  on  .8  pound  of  alfalfa  hay  and 
.8  pound  of  corn  per  head  daily.  On  November  21  this  allowance  was 
decreased  to  .7  pound  of  each  feed  daily  for  all  of  the  lambs  except 
Nos.  75  and  136.  The  same  reduction  was  made  for  Lamb  75  on  No- 
vember 28;  Lamb  136  was  carried  thruout  at  the  higher  level.  The 
chemical  composition  of  the  different  samples  of  feeds  collected  at  the 
sheep  barn  and  at  the  Nutrition  Laboratory,  where  the  metabolism 
tests  were  run,  is  given  in  Table  11. 

Results  of  Digestion  and  Metabolism  Trials 

In  the  last  few  weeks  of  the  experiment  each  of  the  maintenance 
lambs  was  subjected  to  a  digestion  and  metabolism  trial  during  which 
feces  and  urine  were  quantitatively  collected  for  10  days.  In  each 
case  the  lambs  had  been  consuming  for  several  weeks  prior  to  the 
collection  period  a  constant  daily  amount  of  feed,  the  same  as  that 
consumed  during  the  time  of  collection  of  excreta.  The  excreta  passed 
during  the  first  day  in  the  metabolism  crate  were  rejected.  The  meta- 
bolism crates  used  have  been  described  in  Bulletin  283  from  this  Sta- 
tion. The  coefficients  of  digestibility  for  the  different  nutrients,  com- 
puted according  to  the  ordinary  method,  have  been  summarized  in 
Table  12. 

In  addition  to  the  routine  analyses  of  feed  and  feces,  the  gross 
energy  was  also  determined  in  these  samples,  as  well  as  in  the  urine, 
by  combustion  in  the  bomb  calorimeter.  These  determinations  per- 
mitted the  computation  of  the  metabolizable  energy  in  the  mainten- 
ance rations  (Table  13).  The  nitrogen  balances  of  the  lambs  during 
the  metabolism  trials  are  shown  in  Table  14.  All  lambs  were  storing 
nitrogen. 

An  average  of  59.7  percent  of  the  gross  energy  of  the  ration  was 
metabolizable.  Armsby  has  computed1  from  his  own  experiments  on 
steers  that  the  gross  energy  of  alfalfa  is  44  percent  metabolizable  and 
that  of  corn  75  percent  metabolizable.  For  a  ration  containing  ap- 
proximately equal  amounts  of  gross  energy  from  these  two  feeds,  as 
was  true  of  the  ration  fed  the  maintenance  lambs,  one  would  expect 
with  steers  that  59.5  percent  (average  of  44  and  75)  of  the  gross 
energy  would  be  metabolizable,  a  value  practically  identical  with  the 
average  percentage  actually  obtained  with  the  maintenance  lambs. 
Forbes  and  associates  have  recently  reported2  some  energy  metabolism 
studies  on  two  steers  receiving  a  ration  containing  equal  parts  of  alfalfa 


'Arinshy,  H.  P.    Tho  nutrition  of  farm  animals,  661.    Macmillan.  1917. 
"Forbes,  E.  B.,  ct  al.    Amer.  Soc.  Anim.  Prod.  Proc.,  1927. 


1928} 


THE  MAINTENANCE  AND  FATTENING  OF  LAMBS 


39 


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Description  of 
feed  sample 

i'i^'C'u 

I''ed  at  barn  
Metabiilism  trial1  .  . 
Metabolism  trials2.  . 
Metabolism  trials3.  . 
l'Vd  at  barn  

—  re 
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metaboliam  trial 

40  Buiuocr  Na  3M 

.-•'--"         ~  -  "       -       -     -        LAMBS 


•rita 

- 

••MM 

- 
proteia 

- 

Crud« 

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•  - 

ft 

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!*«*• 

fwnri. 

- 

• 

1 

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sa 

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60 

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- 

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59 

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" 

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--  : 

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gross 

maintei  cioi  •  .        .'  ' 

-        ,  t.    These  1         ~  sely  with  thos 

- 


Di:".v  Iz:^ke  c:  Feed  and  E~ergy 

i 
ring  the  main1  \  r  100 

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100.  _  body 

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-  -     _ 

mus  -     .  -     .         •  .    _  •       .     •  .  .  _  -         -      2       st  g 

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. 

-  is  th<         "      : 

T  .  _  "       ould  be 

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-  •.  -  • 

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tained only  by  «;  v;^r.:ering  and  analyzing  the  maintenance  lambs  and 
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,  -  .   -  . 

\ 

Composition  of  the  Maintenance  Lambs 

iin- 
tenance  lan'r  -  ir-  given  in  Tables  16.  17.  18.  and  19.  "With  this  group 


- 


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42 


BULLETIN  No.  314 


[August, 


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THE  MAINTENANCE  AND  FATTENING  OF  LAMBS 


43 


TABLE  16. — SLAUGHTER  DATA  FROM  THE  MAINTENANCE  LAMBS 

(All  weights  in  pounds) 


136 

85 

75 

22 

10 

25 

11 

43 

Aver- 

age 

Live  weight  

72.8 

72.4 

69.0 

71.7 

69.4 

71.6 

73.2 

74  9 

71  9 

Wool  

2  80 

4  00 

3  90 

5  25 

4  50 

6  65 

4  75 

4  91 

4  60 

Blood  

2.80 

3.25 

4.10 

3.70 

2.90 

3.20 

3  00 

3   17 

3  27 

8  50 

7  20 

5  70 

6  50 

5   15 

6  35 

6  66 

6  83 

6  61 

Caul  fat.  . 

.80 

1.60 

1.50 

1   55 

1  35 

1  75 

1  69 

1  46 

1  46 

Gut  fat  

.80 

1.10 

1.35 

1.25 

1.40 

1.10 

1  24 

1   02 

1   16 

Contents  of  first  three 

5.15 

5   15 

4.70 

5  40 

3  65 

5  05 

5  29 

5  45 

4  98. 

Contents  of  4th  stomach 

3  90 

2  55 

3  05 

2  55 

2  00 

2   15 

3  07 

3  40 

2  8$ 

Contents  of  entire 
alimentary  tract  
Warm  dressed  carcass.  . 
Cold  dressed  carcass  .... 
Percent  shrinkage  

9.05 
37.00 
36.08 
2.49 

7.70 
37.50 
36.90 
1.60 

7.75 
35.50 
34.60 
2.54 

7.95 
35.75 
34.86 
2.49 

5.65 
39.50 
38.91 
1.49 

7.20 
37.25 
36.55 
1.88 

8.36 
36.75 
35.03 
4.68 

8.85 
37.75 
36.86 
2.36 

7.81 
37.1$ 
36.22 
2.44 

Percent  "fill" 

12  4 

10  6 

11   2 

11   1 

8   1 

10   1 

11  4 

11   8 

10  8 

Dressing  percentage.  .  .  . 

49.5 

51.0 

50.2 

48.6 

56.1 

51.1 

47.8 

49.2 

50.4 

TABLE  17. — WEIGHTS  OF  SAMPLES  ANALYZED  FROM  THE  MAINTENANCE  LAMBS 


Lamb 

Empty 

Edible  flesh 

Offal 

Wnnl 

No. 

weight 

Lean 

Fat 

Total 

136..  . 

kgs. 
28.94 

grams 
10  767 

grams 
2  614 

grams 
13  381 

grams 
3  998 

grams 

8  838 

grams 
1  270 

85 

29  34 

9  989 

2  960 

12  949 

3  970 

8  155 

1  814 

75. 

27  76 

10  677 

1  740 

12  417 

•     4   178 

8  672 

1  769 

22...  . 
10...  . 
25...  . 
11...  . 
43...  . 

Average.. 

28  .  94 
28.91 
29.21 
29.43 
29.96 

29.08 

10  427 
10  399 
10  136 

9  59S 
9  944 

10  242 

2  125 
4  051 
3  304 
3  262 
3  462 

2  940 

12  552 
14  450 
13  440 
12  860 
13  406 

13  182 

4   116 
3  529 
3  791 
4  248 
4  311 

4  018 

8  915 

7  725 
8  530 
8  528 
8  610 

8  497 

2  381 
2  041 
3  016 
2  155 
2  227 

2  084 

three  instead  of  two  samples  were  taken  from  each  carcass  besides 
the  composite  wool  sample  for  the  group.  The  sample  of  edible  flesh 
represented  the  lean,  including  the  kidneys,  and  the  fat  from  the 
dressed  carcass.  The  bone  sample  included  the  bones  of  the  dressed 
carcass  and  the  bones  of  the  head  and  feet,  as  roughly  cleaned  with  a 
butcher  knife.  The  offal  sample  contained  the  blood,  the  shorn  skin, 
and  the  flesh,  brain,  and  eyes  from  the  head,  together  with  all  viscera 
and  visceral  fat. 

It  is  evident  from  Tables  9  and  19  that  the  carcasses  of  the  main- 
tenance lambs  were  appreciably  fatter  than  those  of  the  check  lambs. 
On  the  live-weight  basis  the  maintenance  lambs  contained  19.25  per- 
cent of  fat  as  compared  with  11.90  percent  for  the  check  lambs;  on 
the  basis  of  the  empty  weight  these  percentages  were  21.57  and  14.15 
respectively.  The  increase  in  weight  of  the  maintenance  lambs  thru- 
out  their  feeding  period  increased  still  further  the  storage  of  energy  in 
their  bodies.  Evidently  the  ration  fed  was  appreciably  greater  in 
energy  value  than  the  lambs  required  for  the  maintenance  of  energy 
equilibrium.  An  attempt  to  correct  the  ration  fed  to  energy  equili- 
brium has  been  made  in  Table  20. 


44 


BULLETIN  No.  314 


[August, 


TABLE  18. — PERCENTAGE  COMPOSITION  AND  ENERGY  VALUE  OF  SAMPLES 
ANALYZED  FROM  THE  MAINTENANCE  LAMBS 


Lamb 

No. 

Dry 

substance 

Crude 
protein 

Ether 
extract 

Ash 

Calcium 

Calcium 
in  percent 
of  total 
ash 

Gross 
energy 
per  gram 

Edible  flesh  samples 


136... 

49  53 

15  38 

26  68 

.91 

.025 

2.75 

sm.  cals. 
3374 

85  

49.49 

15.13 

27.83 

.82 

.027 

3.29 

3612 

75  . 

41  32 

16  63 

21  91 

89 

026 

2  92 

3033 

22  

39  61 

16  56 

22  57 

.87 

.027 

3.  10 

3066 

10  

47.36 

14.88 

32.03 

.77 

.025 

3.25 

3777 

25.  . 

45  47 

15  38 

30  31 

.79 

.030 

3.80 

3706 

11  

49  04 

15  00 

32.81 

.76 

.026 

3.42 

3820 

43. 

49  24 

15  31 

28  63 

83 

023 

2  77 

3551 

Average.  .  .  . 

46.38 

15.53 

27.85 

.83 

.026 

3.16 

3492 

Bone  samples 


136 

60.79 
59.90 
58.66 
58.24 
57  .  84 
60.40 
55.74 
57.74 

58.66 

19.17 
19.52 
19.51 
19.38 
18.96 
19.38 
18.02 
19.31 

19.16       - 

17.96 
19.77 
18.44 
17.31 
16.71 
20.86 
19.77 
18.59 

18.68 

20.90 
18.78 
18.64 
18.73 
19.55 
18.21 
16.41 
18.35 

18.70 

7.84 
7.09 
7.03 
7.00 
7.33 
6.72 
6.14 
6.99 

7.02 

37  .  5 
37.8 
37.7 
37.4 
37.5 
36.9 
37.4 
38.1 

37.  5 

2862 
3115 
2905 
2781 
2679 
3092 
2816 
2802 

2882 

85  

75 

22. 

10  

25 

11.  .. 

43 

Average.  .  .  . 

Offal  samples 

136 

31.89 
35.99 
36.53 
35.99 
43.01 
38.94 
39.08 
36.  3S 

37.23 

15.2.5 
15.25 
13.19 
13.81 
14.38 
14.56 
13.94 
15.00 

14.42 

15.51 
18.43 
21.04 
18.74 
21.50 
20.51 
21.21 
18.04 

19.37 

.91 
1.09 
.97 
1.09 
.99 
.94 
.98 
1.05 

1.00 

.026 
.030 
.035 
.023 
.034 
.026 
.022 
.029 

.028 

2.86 
2.75 
3.61 
2.11 
3.43 
2.77 
2.24 
2.76 

2.82 

2319 
2650 
2674 
2639 

2914 
2889 
2811 
2524 

2678 

85.. 

75 

22 

10  

25 

11 

43... 

1 

Average.  .  .  . 

Wool  samples 

136-43  

91.57 

60.63 

8.60 

11.6 

.177 

1.53 

4460 

Changes  in  Energy  Content  of  the  Maintenance  Lambs 

The  carcasses  of  the  maintenance  lambs  contained  an  average  of 
89.9  therms  of  gross  energy.  Assuming  that  their  energy  content  at 
the  beginning  of  the  feeding  period  was  the  same  as  that  of  the  check 
lambs  at  slaughter,  i.e.,  894  calories  per  pound,  the  initial  energy  con- 
tent of  the  maintenance  lambs  may  be  estimated;  this  has  been  done 
in  Table  20,  giving  an  average  estimate  of  56.4  therms.  Hence  during 
the  period  of  feeding,  the  maintenance  lambs  added  some  33.5  therms 
of  gross  energy  to  their  bodies  at  the  rate  of  252  calories  per  day.  The 
daily  ration  therefore  provided  252  calories  of  net  energy  in  excess  of 
the  maintenance  requirements.  It  may  be  estimated  from  Armsby's 
data1  that  the  metabolizable  energy  of  a  ration  consisting  of  equal 


'The  average  gross  energy  of  the  alfalfa  hay  consumed  by  the  maintenance 
sheep  was  4,108  calories  per  kilogram   and  that  of  the  corn,  3.986  calories   per 


1928} 


THE  MAINTENANCE  AND  FATTENING  OF  LAMBS 


45 


TABLE  19.  —  PERCENTAGE  COMPOSITION  AND  GROSS  ENERGY 
CONTENT  OF  THE  MAINTENANCE  LAMBS 


Lamb 

No. 

Dry 
substance 

Crude 
protein 

Ether 
extract 

Ash 

Calcium 

Calcium 
in  percent 
of  total 
ash 

Gross 
energy 
per  gram 

On  basis  of  live  weight 

136... 

39.47 
41.42 
39.55 
39.19 
44.73    • 
44.61 
42.07 
41.97 

41.63 

14.96 
15.75 
16.29 
17.05 
16.42 
18.09 
15.62 
16.26 

16.31 

17.46 
18.76 
17.48 
16.65 
22.42 
21.17 
21.23 
18.79 

J9.25 

3.58 
3.53 
3.77 
3.85 
3.54 
3.78 
3.40 
3.68 

3.64 

.97 

.88 
.97 
.92 
.85 
.82 
.81 
.91 

.88 

28.0 
24.8 
25.5 
23.6 
23.7 
21.5 
23.6 
24.5 

24.4 

SOT.  cals. 
2  504 
2  754 
2  586 
2  583 
3  039 
3  068 
2  849 
2  688 

2  759 

85  

75 

22     . 

10  

25 

11 

43  

Average.  .  .  . 

On  basis  of  empty  weight 

136 

45.06 
46.35 
44.56 
44.08 
48.69 
49.59 
47.51 
47.60 

46.68 

17.08 
17.62 
18.36 
19.18 
17.87 
20.11 
17.64 
18.44 

18.29 

19.93 
20.99 
19.70 
18.73 
24.40 
23.53 
23.97 
21.31 

21.57 

4.09 
3.95 
4.25 
4.33 
3.85 
4.20 
3.84 
4.17 

4.09 

1.11 
.99 
1.09 
1.03 
.93 
.91 
.92 
1.03 

1.00 

2  859 
3  082 
2  914 
2  905 
3  308 
3  410 
3  217 
3  049 

3  093 

85 

75  .        ... 

22  

10 

25 

11  

43 

Average.  .  .  . 

parts  of  alfalfa  hay  and  corn  is  53  percent  net  available.  Forbes  and 
associates  (loc.  cit.)  have  more  recently  investigated  directly  the  utili- 
zation of  the  energy  of  this  ration  on  two  steers.  From  the  data  ob- 
tained it  may  be  computed  that  the  metabolizable  energy  equivalent  to 
one-half  the  maintenance  requirement  of  steers,  when  added  to  a  main- 
tenance ration,  increased  the  energy  balance  by  an  amount  equal  to 
55.4  and  55.7  of  the  added  metabolizable  energy.  In  other  words,  be- 
tween a  maintenance  level  of  feeding  and  a  level  50  percent  higher,  the 
metabolizable  energy  appeared  to  have  a  net  availability  of  a  little 
over  55  percent.  This  percentage  is  in  close  agreement  with  the  value 
obtained  from  Armsby's  data  and  has  been  used  in  the  calculations  of 
Table  20. 

Corrected  Maintenance  Requirements 

Assuming,  therefore,  that  the  metabolizable  energy  consumed  by 
these  lambs  above  their  maintenance  requirements  possessed  a  per- 


kilognim.  Of  the  gross  energy  of  alfalfa  hay  44  percent  is  available  as  metaboliz- 
able energy,  and  of  corn  75  percent  is  available  (see  page  38).  Of  the  metaboliz- 
able energy  in  these  feeds  the  percentage  available  as  net  energy  for  fattening  is 
(Armsby,  "The  Nutrition  of  Farm  Animals,''  page  661)  for  alfalfa  hay  39  percent 
and  for  corn  61  percent.  Each  kilogram  of  alfalfa  hay  therefore,  contained  4,108 
X  .44,  or  1,808  calories  of  metabolizable  energy,  and  1,808  X  .39,  or  705  calories  of 
net  energy:  and  each  kilogram  of  corn  contained  3,986  X  .75,  or  2.900  calorics  of 
metabolizable  energy,  and  2,900  X  .61,  or  1,769  calories  of  net  energy.  The  aver- 
age net  availability  of  the  metabolizable  energy  of  a  ration  containing  equal  parts 

705  +  1,769 


of  these  two  feeds  is  therefore 


1,808  +  2,900 


=52-55 


46 


BULLETIN  Xo.  314 


[August. 


Average 

O       OTiS 
—                                    IS  CM                   T 

£0 

CM        CO  to 

—        O  T 

iverage  gross 
it  was  found 
nance  lambs, 
nergy  intake, 
•ed  energy. 

g 

is      t-  >-*  t- 

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cote 

t~iO 

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ft       CCO 

p  had.  The 
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y  the  mainte 
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valent  of  sto 

iO 
X 

O        T  —  CO 

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CO  b-        OS  >O  CO        IS  T         IS        T 

b-  CO 

§b-o          —  — 
0  — 

—      i.o  -r 

le  check  shee 
of  the  maint 
•  consumed  b 
s  the  daily  in 
e  energy  equ 

iO 

-H     ocoo 

—  '  r-       O  O  T       TX       iS       M 
CO  O         X  iS  M         X  X         'S        T 

—                                    iS—                   CO 

COM 

M        —  X             —  — 

T        i.O  M 

CM        X  O 

e  weight  as  t 
ibolism  trials 
1  gross  energ; 
by  .filtS  givi 
inetabolizab 

CO 

CO        CO  T  S: 
iO  0        —  is"  O        CX        IS        — 

TO     c;  is  co     r~  T     »o      uo 

—                                    iS  M                   T 

C1CO 

C:        iO  M             —  — 

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.0 
M 

O       OC  0 

—  e     os  o  o     -HO     is     T 

CO  t—        S:  iO  T        IO  —        i.O        O 
—                                    is  CO                   iS 

f~        X  CO             —  '  — 

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O        CO  M 

~  "    5  'f.  r 

IN 

•N 

—  S       T  X  O       iO  X       is       C! 
CO  h-        X  iO  M        iO  O        i-O        O 
—                                    iS  —                   CO 

~OT 

the  same  gn 
S(t4  calories  p 
ble  as  metal) 
>f  gross  encrg 
'Daily  ineta 

= 

iS  ~.       T  0  X       C  T       is       p 

O        iO  i.O             t—  i  >—  1 

— 

M        O  —  'O 

~  •£     '-;  •£  t;     '3  ~     '3     —  ' 

*~<                                    i-O  CM                   1*0 

>0        X  0             -H  — 

CO        —CO 
O       'S  CO 

p  at  their  initi 
er  kilogram  of  li 
energy  consun 
lent  gives  the 
bolizable  energ 

c. 

3 

:    ;  a 

c 

O 

fc 

.0 

Feeding  period,  days  
Average  body  weight,  pounds  
dross  energy  content,  the!  ins 
Final  
Initial'  
(  lain  
Daily  intake  of  metabolizable  energy 
calories2  
Daily  storage  of  energy,  calories.  .  .  . 
Assumed  availability  of  metabolizabl 
energy  of  the  ration,  percent  
Metabolizable  energy  equivalent  of  t 
stored  energy,3  calories  
Maintenance  requirements  of  metalx 
energy  daily,  calories 

Per  bead*  
J'er  100  pounds  live  weight: 
Weight  ratio  
Surface  ratio  
Maintenance  requirements  of  ration,! 
per  100  pounds  live  weight: 
Weight  ratio  
Surface  ratio  

'Assuming  that  the  niaintenan 
energy  of  the  check  sheep  was  1971  ci 
that  an  average  of  5!).S  percent  of  tl 
divided  by  the  number  of  days  on 
8Daily  energy  storage  divided  by  .  .r>5 

192S]  THE  MAINTENANCE  AND  FATTENING  OF  LAMBS  47 

centage  availability  of  55,  the  daily  net  energy  stored,  averaging  252 
calories,  may  be  taken  as  equivalent  to  458  calories  of  metabolizablc 
energy.  The  daily  intake  of  metabolizable  energy  averaged  1,586 
calories,  so  that  the  maintenance  requirement  becomes  1,586  —  458 
=1,128  calories  per  head,  or  1,637  calories  per  100  pounds  body  weight 
computed  in  proportion  to  weight,  or  1,461  calories  per  100  pounds 
computed  in  proportion  to  the  two-thirds  power  of  the  weight  (body 
surface).  The  quantity  of  feed  has  been  computed  from  these  values 
by  means  of  the  average  metabolizable  energy  content  of  the  ration 
(1,074  calories  per  pound). 

The  choice  between  the  two  estimates  of  the  maintenance  require- 
ment of  metabolizable  energy  is  a  difficult  one,  depending  as  explained 
above  on  the  proportions  of  energy  used  for  the  basal  metabolism  and 
for  muscular  activity.  These  are  unknown.  It  would  be  expected 
that  the  more  significant  method  of  reducing  these  estimated  require- 
ments to  a  body  weight  of  100  pounds  would  give  the  less  variable  set 
of  values.  The  standard  deviation  of  the  estimates  made  in  accord- 
ance with  the  ratio  of  weights  is  226  calories,  while  that  of  the  esti- 
mates made  in  accordance  with  the  ratio  of  surfaces  is  203  calories. 
However,  the  coefficients  of  variation  are  practically  the  same,  14.4 
and  14.5  percent  respectively,  so  that  a  choice  between  the  two  meth- 
ods on  this  basis  can  hardly  be  made. 

On  a  ration  of  alfalfa  hay  alone  it  was  found  in  the  preceding 
investigation  with  older  sheep  (see  Illinois  Bulletin  283) ,  that  the  main- 
tenance requirement  averaged,  for  12  sheep,  1,820  calories  of  metabo- 
lizable energy  per  100  pounds  live  weight  by  using  the  ratio  of  weights, 
and  1,733  calories  by  using  the  ratio  of  surfaces.  These  figures  are  ap- 
preciably higher  than  those  computed  in  the  present  experiment,  a  fact 
that  may  reasonably  be  accounted  for  by  the  known  poorer  utilization 
of  the  metabolizable  energy  of  alfalfa  hay  than  of  corn. 

Net  Energy  Required  for  Maintenance 

Forbes  and  associates  (loc.  cit.)  found  that  the  metabolizable  en- 
ergy of  a  maintenance  ration  of  equal  parts  of  alfalfa  hay  and  corn 
was  80.8  percent  net  available  for  one  of  their  steers  (No.  47)  and 
81.4  percent  net  available  for  the  other.  If  lambs  may  be  assumed  to 
be  equally  efficient  in  the  utilization  of  the  metabolizable  energy  of 
a  similar  maintenance  ration,  the  net  energy  requirement  of  the  lambs 
may  be  computed  for  "economic  maintenance."  Applying  the  average 
of  the  two  percentages  obtained  with  steers  to  the  average  metaboliz- 
able energy  requirements  given  in  Table  20  gives  a  net  energy  require- 
ment of  1,326  calories  per  100  pounds  live  weight  according  to  the 
ratio  of  weights  and  1,183  calories  according  to  the  ratio  of  surfaces. 

Wood  and  Capstick1  have  recently  calculated  by  an  indirect  matho- 


'Wood.  T.  B.,  and  Capstick.  J.  W.    Jour.  Apr.  Sci.  16,  325.   1926. 


48 


BULLETIN  Xo.  314 


[August, 


matical  method  that  a  sheep  weighing  100  pounds  requires  daily  for 
maintenance  1.26  pounds  of  starch  equivalent,  or  1,348  calories  of  net 
energy.  This  value  was  computed  in  proportion  to  the  surface  of  the 
sheep  and  is  therefore  to  be  compared  with  the  estimate  of  1,183 
calories  in  this  experiment.  Wood  and  Capstick  obtained  their  value 
by  a  mathematical  analysis  of  data  concerning  the  feed  consumption 
and  the  variations  in  weight  of  twenty-eight  sheep.  The  starch  values 
of  the  feed  consumed  were  apparently  calculated  from  the  average 
tables  of  Kellner  for  fattening  steers. 

THE  FATTENING  EXPERIMENT 

On  September  30,  1925,  eight  lambs  averaging  66  pounds  in  weight 
were  put  upon  such  amounts  of  alfalfa  hay  and  corn  in  equal  propor- 
tions as  they  would  readily  clean  up.  On  October  24  a  ninth  lamb  was 
added  to  this  group.  These  lambs  were  slaughtered  at  approximately 
90  pounds  in  order  to  determine  the  nature  of  the  gains  made  during 
fattening  to  a  popular  slaughter  weight  and  the  utilization  of  the 
metabolizable  energy  consumed  and  used  for  that  purpose.  The  week- 
ly weights  of  these  lambs  will  be  found  in  Table  21.  The  average  daily 
gains  varied  from  .18  to  .36  pound  and  averaged  .25  pound. 

The  feed  consumption  of  the  lambs  has  been  summarized  and 
averaged  in  Table  22.  The  feeds  fed  at  the  barns  were  sampled  along 
with  the  feeds  of  the  maintenance  lambs,  and  the  analyses  of  these 
samples  have  been  given  in  Table  11. 

TABLE  21. — WEEKLY  WEIGHTS  OF  LAMBS  DURING  FATTENING  PERIOD1 

(All  weights  in  pounds) 


Lamb  Xo 

33 

69 

151 

169 

67 

49 

54 

90 

143 

1927 

Sept.  30 

70 

67 

69 

66 

65 

66 

65 

65 

Oct.  10 

69 

69 

73 

69 

55 

67 

69 

66 

17 

68 

71 

68 

70 

55 

67 

66 

66 

24 

65' 

73 

71 

72 

76 

61 

71 

70 

07 

31 

66 

72 

71 

71 

73 

60 

70 

70 

69 

N'ov.  7 

71 

73 

80 

72 

81 

71 

76 

79 

75 

14 

70 

SO 

77 

78 

78 

69 

78 

76 

72 

21 

73 

80 

78 

76 

78 

69 

75 

74 

73 

28 

73 

85 

77 

79 

80 

66 

76 

77 

73 

Dec.  5 

74 

87 

7!) 

81 

83 

70 

79 

82 

72 

12 

80 

85 

81 

84 

85 

74 

84 

84 

72 

19 

85 

90 

88 

88 

90 

77 

86 

85 

73 

26 

35 

86 

88 

78 

89 

87 

79 

1926 

Jan.  2 

91 

90 

91 

82 

92 

91 

82 

9 

83 

83 

16 

86 

86 

23 

86 

85 

30 

83 

86 

Feb.  6 

85 

90 

13 

87 

17 

90 

Average  weights 

75  7 

77.7 

77  5 

77  9 

77.4 

73  9 

76  9 

76  8 

75  5 

Average  daily  gains.  .  .  . 
Length  of  feeding  period 

.36 

.24 

.24 

.'23 

'.29 

!l8 

27 

27 

.'l9 

in  days  

73 

82 

97 

97 

82 

141 

97 

97 

131 

'Lambs  67  and  69  were  slaughtered  on  December  21,  1925,  after  82  days  of  feeding;  Lambs 
151,  169,  54,  33,  and  90  were  slaughtered  on  January  5,  1926,  after  97  days  of  feeding;  Lamb  143  was 
killed  on  February  8,  and  Lamb  49  on  February  18,  after  131  and  141  days  of  feeding,  respectively. 


1928] 


THE  MAINTENANCE  AND  FATTENING  OF  LAMBS 


49 


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50 


BULLETIN  No.  314 


[August, 


Results  of  the  Digestion  and  Metabolism  Trials 

During  the  period  from  October  29  to  December  5  digestion  and 
metabolism  trials  were  made  upon  five  of  the  nine  fattening  sheep.  As 
with  the  maintenance  lambs,  the  collection  periods  were  of  10  days 
duration.  For  two  of  the  lambs  (Nos.  69  and  169)  no  change  in  feed 
had  been  made  for  29  days  before  the  collection  period.  For  Lamb 
33  the  feed  had  been  constant  for  nine  days  preceding  the  digestion 
experiment,  while  for  Lambs  67  and  151,  it  had  been  raised  from  2.0 
to  2.4  pounds  daily  on  the  second  day  preceding  the  collection  period. 
The  latter  two  lambs  should  not  have  been  put  on  a  digestion  exper- 
iment so  soon  after  a  change  of  feed,  but  nevertheless  the  results  ob- 
tained in  these  cases  agreed  well  with  the  results  obtained  upon  the 
other  lambs.  Except  on  the  final  day  of  collection  with  Lamb  67,  there 
was  no  refused  feed  in  these  digestion  experiments. 

The  chemical  composition  of  samples  of  feed  taken  during  the 
digestion  and  metabolism  trials  is  given  in  Table  23.  The  alfalfa  hay 
fed  in  these  trials  was  somewhat  drier  than  that  fed  at  the  barn  (see 
Table  11)  and  somewhat  higher  in  protein,  but  the  corn  fed  was  very 
similar  in  composition  to  the  composite  samples  taken  at  the  barns. 

In  Table  24  the  coefficients  of  digestibility  of  the  nutrients  in  the 
ration,  as  computed  in  the  ordinary  way,  have  been  summarized.  A 
comparison  of  the  average  coefficients  obtained  with  these  fattening 
lambs  and  those  obtained  with  the  maintenance  group  consuming  the 

TABLE  23. — CHEMICAL  COMPOSITION  OF  FEED  CONSUMED  BY  THE  FATTENING  LAMBS 
DURING  DIGESTION  AND  METABOLISM  TRIALS 


Dry 

Gross 

Lamb  No. 

sub- 
stance 

Crude 
protein 

N-free 
extract 

Crude 
fiber 

Ether 
extract 

Ash 

Cal- 
cium 

energy 
per 

gram 

Alfalfa  hay 


69,  169.. 

perct. 

92  67 

perct. 
18  25 

perct. 
41   97 

perct. 
22  03 

perct. 
2  34 

perct. 
8  08 

perct. 

sm.  cals. 
4172 

67,  151  

93  54 

17  38 

39  67 

25   11 

2   17 

9  21 

1   44 

4215 

33  

93.51 

17.06 

43.61 

22.98 

2.37 

7.49 

1.52 

4158 

Corn 


69,  169 

88  93 

8  56 

73  55 

2  19 

3  37 

1  96 

3984 

67,  151..  . 

87  54 

8  73 

71  86 

2  50 

3  18 

1  27 

3935 

33  

87.56 

8.56 

72.09 

2.23 

3.54 

1.14 

3918 

TABLE  24. — DIGESTION  COEFFICIENTS  OBTAINED  WITH  THE  FATTENING  LAMBS 


Lamb 

No. 

Dry 
substance 

Crude 
protein 

N-free 
extract 

Crude 

fiber 

Ether 
extract 

69  

perct. 
77 

perct. 
73 

perct. 
89 

perct. 
36 

perct. 
66 

169  

75 

71 

88 

28 

65 

67  

76 

70 

89 

35 

62 

151  

76 

72 

89 

36 

62 

33.... 

75 

68 

87 

49 

60 

Average  

75.8 

70.8 

88.4 

35.4 

63.0 

THE  MAINTENANCE  AND  FATTENING;  OF  LAMBS  51 

same  ration  at  a  different  level  may  be  made  by  turning  to  Table  12. 
In  general  a  higher  digestibility  was  obtained  with  the  fattening  lambs. 

The  determination  of  the  gross  energy  of  feed  and  excreta  in  these 
digestion  experiments  permits  the  calculation  of  the  metabolizable 
energy  content  of  the  ration,  the  methane  excretion  being  estimated, 
according  to  Armsby's  method  for  steers,  from  the  digestible  carbo- 
hydrates consumed.  These  calculations  will  be  found  in  Table  25. 
For  the  fattening  lambs  the  ration  contained  2.794  therms  per  kilo- 
gram of  dry  matter,  as  compared  with  an  average  of  2.653  therms  ob- 
tained with  the  maintenance  lambs  (Table  13).  For  the  fattening 
lambs  the  gross  energy  of  the  ration  was  62.27  percent  metabolizable 
on  the  average,  as  compared  with  59.74  percent,  for  the  maintenance 
lambs. 

The  fattening  lambs  were  all  storing  nitrogen  during  the  collec- 
tion periods  according  to  the  data  assembled  in  Table  26. 

Composition  of  the  Fat  Lambs 

At  the  end  of  feeding  periods  varying  in  length  from  73  days  to 
141  days,  the  nine  fattened  lambs  were  slaughtered  at  weights  of  ap- 
proximately 90  pounds.  The  method  of  sampling  was  essentially  the 
same  as  that  followed  with  the  maintenance  lambs.  For  each  lamb 
there  were  three  samples  consisting  of  edible  flesh,  bone,  and  offal,  and 
for  all  lambs  slaughtered  on  the  same  day  a  composite  sample  of  wool 
was  taken.  Slight  irregularities  in  the  disposition  of  the  bones  of  the 
head  and  feet,  as  between  the  bone  and  the  offal  samples,  resulted  thru 
inadvertance,  but  these  did  not  affect  the  accuracy  of  the  final  com- 
putations. These  irregularities  are  all  noted  in  the  tables.  The  slaugh- 
ter data  for  these  lambs,  the  weights  of  samples,  the  results  of  the 
analysis  of  the  samples,  and  the  estimated  composition  of  the  total 
animals  on  the  live-weight  and  empty-weight  basis  are  given  in  Tables 
27  to  30.  The  latter  computations,  as  for  all  preceding  groups  of 
lambs,  include  all  possible  corrections  for  losses  of  moisture  during 
slaughtering  and  sampling. 

The  fat  lambs  contained  an  average  ''fill"  of  11.1  percent,  as  com- 
pared with  averages  of  15.9  for  the  check  lambs  and  10.8  for  the  main- 
tenance lambs.  On  the  basis  of  the  empty  weight  the  fat  lambs  con- 
tained an  average  of  24.89  percent  of  fat,  the  maintenance  lambs  21.57 
percent,  and  the  check  lambs  14.15  percent.  The  average  ash  percent- 
ages for  the  three  groups  of  lambs  on  the  same  basis  were  4.17,  4.09, 
and  4.79  respectively.  The  percentage  of  calcium  in  the  ash  of  the 
empty  carcass  averaged  22.3  for  the  fat  lambs,  24.4  for  the  mainten- 
ance lambs,  and  28.5  for  the  check  lambs.  The  first  group  of  check 
lambs  also  showed  a  high  average  for  this  value,  i.e.,  27.4  percent.  In 
the  case  of  rats,  Buckner  and  Peter1  obtained  fairly  constant  percent- 

'Buckner,  G.  D.,  and  Peter,  A.  M.    Jour.  Biol.  Chem.  54,  5.    1922. 


52 


BULLETIN  No.  314 


[August, 


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THE  MAINTENANCE  AND  FATTENING  OF  LAMBS 


53 


TABLE  26. — DAILY  NITROGEN  BALANCES  OF  THE  FATTENING 
LAMBS  DURING  METABOLISM  TRIALS 


Lamb 
No. 

Nitrogen  of 
feed  consumed 

Nitrogen  of 
feces 

Nitrogen  of 
urine 

Total  N 
excreted 

Nitrogen 
balance 

69... 

grams 
19.49 

grams 
5.20 

grams 
10.15 

grams 
15.35 

grams 
+4.14 

169  

19.49 

5.70 

10.39 

16.09 

+3.40 

67  

22.72 

6.90 

11.17 

18.07 

+4.65 

151  

22.72 

6.26 

12.53 

18.79 

+3.93 

33  

18.62 

5.89 

9.72 

15.61 

+3.01 

TABLE  27. — SLAUGHTER  DATA  FOR  THE  FATTENED  LAMBS 

(All  weights  in  pounds) 


Lamb  No  

67 

69 

151 

169 

54 

33 

90 

143 

49 

Live  weight  .... 
Wool   .    . 

87.  4 
5  13 

88.7 
5.94 

85.5 
4  74 

87.8 
6.26 

87.8 
4.84 

84.9 
4.39 

88.8 
4.76 

85.4 
5.35 

84.1 
5.60 

86.7 
5  22 

Blood  

3.56 

3.50 

3.80 

7.67 

3.72 

2.94 

3.56 

3.20 

3.05 

3  89 

Skin  and  feet  .  . 
Caul  fat  . 

7.44 
1  75 

7.00 
2  69 

8.55 
1.85 

6.35 
2  34 

9.19 
1.39 

7.56 
1.65 

8.13 
2.18 

6.65 
2.20 

7.00 
2  90 

7.54 
2  11 

Gut  fat.  .  .    . 

.81 

.81 

.80 

.95 

.70 

1.00 

1.02 

1.65 

1.45 

1.02 

Contents  of 
first  three 
stomachs  .... 
Contents  of  4th 
stomach    and 
intestines.  .  .  . 
Contents  of 
entire  alimen- 
tary tract.  .  . 
Warm  dressed 

8.44 
2.56 

11.00 
46.38 

8.81 
3.00 

11.81 
44.94 

6.25 
2.85 

9.10 
44.75 

4.86 
3.01 

7.87 
45.75 

7.94 
3.41 

11.35 
43.75 

7.58 
2.85 

10.43 
43.50 

5.94 
3.25 

9.19 
46.50 

4.55 
2.80 

7.35 
47.00 

6.80 
2.10 

8.90 
46.00 

6.80 
2.87 

9.67 
45.40 

Cold  dressed 
carcass  

45.90 

44.35 

43.33 

44.20 

42.26 

41.85 

44.88 

45.93 

45.07 

44.20 

Percent 
shrinkage  .... 
Percent  "fill".  . 
Dressing 
percentage.  .  . 

1.03 
12.6 

52.5 

1.31 
13.3 

50.0 

3.17 
10.6 

50.7 

3.39 
9.0 

50.4 

3.41 
12.9 

48.1 

3.79 
12.3 

49.3 

3.48 
10.4 

50.6 

2.28 
8.6 

53.8 

2.02 
10.6 

53.6 

2.65 
11.1 

51.0 

TABLE   28. — WEIGHTS  OF  SAMPLES   ANALYZED   FROM  THE  FATTENED   LAMBS 


Lamb 

Empty 

Edible  flesh 

Offal 

Wool 

No. 

weight 

Lean 

Fat 

Total 

kgs. 

grams 

grams 

grams 

grams 

grams 

grams 

67. 

34.65 

12  108 

5  640 

17  748 

2  703' 

10  989 

2  327 

69. 

34.87 

12  021 

4  974 

16  995 

2  753' 

10  747 

2  694 

151. 

34.65 

11  726 

4  215 

15  941 

4  008  2 

10  657 

2  150 

169. 

36.24 

10  738 

5  682 

16  420 

3  88N  = 

11   101 

2  839 

54. 

34.70 

12  025 

3  452 

15  477 

4  0072 

10  978 

2   195 

33. 

33.77 

11  433 

3  737 

15  170 

4  0702 

10  635 

1  991 

90. 

36.09 

11  918 

4  452 

16  370 

4  0142 

10  890 

2  159 

143. 

35.43 

12  368 

5  175 

17  543 

4  514 

9  420 

2  427 

49. 

34.11 

10  584 

5  885 

16  469 

3  825 

9  910 

2  540 

Average.. 

34.95 

11  658 

4  801 

16  459 

2  369 

•Exclusive  of  bones  of  head  and  of  feet,  which  were  put  in  the  offal  sample.     8>Jot  including 
bones  of  feet,  which  were  put  in  offal  sample. 


ages  of  25  to  26  thruout  the  growing  period.  The  bone  samples  of  both 
the  fat  lambs  and  the  maintenance  lambs  contained  normal  average 
percentages  of  calcium  in  the  ash  (37.6  and  37.5  respectively).  The 
low  ash  content  of  the  bone  samples  as  compared  with  that  of  well- 
calcified  bone  itself  is  to  be  expected  in  view  of  the  imperfect  separa- 
tion of  bone  from  soft  tissues  in  the  preparation  of  these  samples. 


54 


BULLETIN  No.  314 


[August, 


TABLE  29. — PERCENTAGE  COMPOSITION  AND  ENERGY  VALUE  OF  SAMPLES 
ANALYZED  FROM  THE  FATTENED  LAMBS 


Lamb 

No. 

Dry 
substance 

Crude 
protein 

Ether 
extract 

Ash 

Calcium 

Calcium 
in  percent 
of  total 
ash 

Gross 
energy 
per  gram 

Edible  flesh  samples 


67  ... 

51.69 

13.56 

36.86 

1.31 

.020 

1  53 

sm.  cals. 
4  196 

69  

51.66 

13.19 

35.84 

1.18 

.021 

1.78 

4  061 

151   ..      . 

53.61 

14.00 

37.60 

1  03 

.018 

1  75 

4  292 

169  

52.14 

14.56 

34.23 

.98 

.017 

1.73 

4  000 

54  

54.19 

15.56 

28.60 

1.07 

.027 

2.52 

3  421 

33  

53.38 

15.63 

28   11 

1  41 

021 

1  49 

3  422 

90  

51.39 

14.31 

32.94 

1.03 

.020 

1.94 

3  794 

143  

48.88 

15.13 

33.54 

.83 

.021 

2.53 

3  968 

49  .. 

58.59 

14.13 

39.64 

.73 

025 

3  42 

4  398 

Average.  .  .  . 

52.84 

14.45 

34.15 

1.06 

.021 

2.08 

3  950 

Bone  samples1 


67... 

70.42 

19  81 

22.59 

24.75 

9.34 

37  7 

3  349 

69  

69.66 

18.86 

21.79 

24.26 

9.22 

38.0 

3  391 

151 

57  67 

17  69 

18  95 

19  35 

7  25 

37  5 

2  854 

169  

60  79 

18.52 

18.87 

20.32 

7.75 

38.1 

2  904 

54  

58.19 

18.30 

16.56 

21.02 

7.88 

37.5 

2  643 

33 

58  09 

16  51 

19  00 

19.35 

7  24 

37  4 

2  830 

90  

59  32 

18.30 

17.93 

20.80 

7  76 

37  3 

2  796 

143  

60.69 

20.41 

16.23 

21.79 

8.20 

37.6 

2  742 

49 

60  42 

21  27 

16  25 

21  81 

8  17 

37  5 

2  720 

Average.  .  .  . 

61.69 

18.85 

18.69 

21.49 

8.09 

37.6 

2  914 

Offal  samples2 


67  .... 

39  35 

14  50 

20.05 

2.24 

.519 

23.2 

2  759 

69  

38.06 

14  .  56 

17.13 

2.39 

.559 

23.4 

2  527 

151 

36  99 

14  69 

19  87 

1  16 

.061 

5  26 

2  576 

169  . 

37  94 

14  13 

21  98 

1.14 

.061 

5.35 

2  669 

54  

34.48 

15.75 

17.00 

1.28 

.076 

5.94 

2  327 

33 

35  99 

15  50 

19  08 

1  31 

102 

7  79 

2  563 

90  ...   . 

38  46 

14.69 

20.63 

1.14 

.090 

7.89 

2  658 

143  

41.27 

14.94 

23.64 

.92 

.021 

2.28 

3  027 

49 

42  99 

14  69 

24  83 

.95 

.023 

2  42 

3  166 

Average.  .  .  . 

Wool  samples 


67,  69.  ... 

89  35 

60.75 

9.05 

11.34 

.20' 

4  344 

151,  169,  54, 
33,  90  
143,  49  

89.73 
89.62 

60.88 
60.84 

8.83 
8.89 

15.54 
14.34 

.203 
.203 

4  366 
4  374 

'The  samples  for  Lambs  67  and  69  contained  only  the  bones  from  the  dressed  carcass;  those  for 
Lambs  151,  169,  54,  33,  and  90  contained  in  addition  the  bones  of  the  head;  while  those  for  Lambs 
143  and  49  contained  the  bones  of  head  and  feet.  2The  samples  for  Nos.  67  and  69  contained 
the  bones  from  the  head  and  feet;  those  for  Nos.  151, 169,  54,  33,  and  90  contained  the  bones  of  the  feet; 
while  those  for  Nos.  143  and  49  contained  only  the  viscera  and  other  waste.  3The  average  calcium 
content  of  a  composite  sample  of  wool  from  all  fat  sheep. 

In  Table  30,  the  nine  fat  lambs  are  arranged  in  the  order  of  their 
slaughter.  No  progressive  differences  in  composition  are  evident,  so 
that  the  data  obtained  do  not  indicate  that  the  rapid  gains  are  ap- 
preciably different  in  composition  from  the  slow  gains. 

Composition  of  the  Gains  in  Weight 

On  the  assumption  that  the  fat  lambs  at  their  initial  weights 
possessed  the  same  composition  on  the  live-weight  basis  as  the  second 


IMS] 


THE  MAINTENANCE  AND  FATTENING  OF  LAMBS 


55 


TABLE  30. — PERCENTAGE  COMPOSITION  AND  GROSS  ENERGY 
CONTENT  OF  THE  FATTENED  LAMBS1 


Calcium 

Gross 

Lamb 
No. 

Dry 
substance 

Crude 
protein 

Ether 
extract 

Ash 

Calcium 

in  percent 
of  total 

energy 
per  gram 

ash 

On  basis  of  live  weight 


67... 

44.10 

15.01 

24.14 

3.56 

.80 

sm.  cats. 
2  492 

69 

42  74 

14  82 

21  82 

3  56 

80 

2  914 

151 

43  14 

15  00 

23  37 

3  61 

78 

3  010 

169  

44.43 

16.10 

22  47 

3.82 

.79 

2  988 

54  

41.34 

15.58 

17.96 

3.74 

.84 

2  476 

33 

41  76 

15  33 

18  82 

3  77 

81 

2  582 

90  

42  02 

14.89 

21  24 

3  61 

.82 

2  775 

143  

44.84 

16.65 

23.37 

4.03 

.98 

3  125 

49 

48  49 

16  10 

25  78 

3  70 

85 

3  285 

Average.  .  .  . 

43.65 

15.50 

22.10 

3.71 

.83 

2  849 

On  basis  of  empty  weight 


67  . 

50  45 

17  17 

27  61 

4  07 

92 

22  6 

2  851 

69  

49  31 

17  10 

25  17 

4.10 

.93 

22  7 

3  361 

151  

48.28 

16  78 

26  15 

4.04 

.87 

21.6 

3  368 

169 

48  80 

17  68 

24  96 

4  19 

87 

20  7 

3  284 

.~)4  . 

47  48 

17  88 

20  61 

4  29 

96 

21  9 

2  844 

33  

47.61 

17  48 

21  45 

4.29 

.93 

21.7 

2  943 

90  

46.88 

16.60 

23.69 

4.03 

.91 

22.2 

3  095 

143 

49  06 

18  23 

25  57 

4  41 

1  07 

24  3 

3  419 

49  .   ... 

54.22 

18  01 

28  84 

4  14 

.95 

22.9 

3  674 

Average.  .  .  . 

49.12 

17.43 

24.89 

4.17 

.94 

22.3 

3  205 

'Xos.  67  and  69  were  killed  after  82  days  of  feeding;  151,  169,  54,  33,  and  90  after  97  days;  143 
after  131  days;  and  49  after  141  days  of  feeding. 

group  of  check  lambs  (Table  9),  it  is  possible  to  compute  the  compo- 
sition of  the  gains  put  on  during  the  fattening  period.  The  results  of 
such  a  calculation,  expressed  as  percentages  of  the  estimated  increase 
in  empty  weight,  are  given  in  Table  31.  The  great  variation  among  the 
individual  estimates  is  due  not  only  to  the  differences  in  the  actual 
composition  of  gains  but  also  to  the  not  inconsiderable  error  in  the 
method  of  estimation,  according  to  which  all  of  the  lambs  are  assumed 
to  possess  the  same  initial  composition. 

The  average  gain  in  empty  weight  from  about  65  to  about  90 
pounds  contained  75.1  percent  of  dry  matter,  11.9  percent  of  crude 

TABLE  31. — ESTIMATED  PERCENTAGE  COMPOSITION  AND  ENERGY  VALUE 
OF  GAINS  IN  EMPTY  WEIGHT  PUT  ON  BY  THE  FATTENED  LAMBS 


Lamb 

Xo. 

Dry 

substance 

Crude 
protein 

Ether 
extract 

Ash 

Gross  energy 
per  pound 

67 

79.8 

10  9 

63  4 

2  1 

therms 
3  11 

69  

81.8 

9.2 

61.2 

1  8 

3  03 

151 

73  3 

9   1 

59  9 

2  0 

2  83 

169       

73.7 

12.9 

53  7 

2  6 

2  62 

54  

68.8 

13.5 

37.6 

3.0 

1  89 

33 

70  3 

11.8 

41   5 

2  9 

2  08 

90  

63.3 

10.2 

44.6 

2  3 

2  15 

143 

71  5 

15  3 

52  2 

3  6 

2  68 

49     

93.3 

14.0 

67.8 

2  5 

3.27 

Average  

75.1 

11.9 

53.6 

2.5 

2.63 

56 


BULLETIN  No.  314 


[August, 


protein,  53.6  percent  of  fat,  and  2.5  percent  of  ash.  The  computations 
for  calcium  indicated  no  increase  in  the  store  of  this  mineral.  The  nine 
lambs  contained  an  average  of  327  grams  of  calcium  at  slaughter  and 
were  estimated  to  have  contained  an  average  of  344  grams  initially.  It 
seems  improbable  that  no  calcium  was  stored  during  the  fattening 
period.  A  slight  storage,  however,  may  have  been  obscured  by  the 
possible  error  in  the  estimation  of  the  initial  calcium  composition  of 
the  lambs. 

Each  pound  of  gain  in  empty  weight  contained  on  the  average 
2.63  therms  of  gross  energy.  This  value  is  less  than  the  average  value 
of  3.25  therms  given  by  Armsby  to  the  energy  content  of  a  pound  of 
gain  by  fattening  animals,  but  is  almost  identical  with  the  value  re- 
ported by  Wood1  for  two  sheep  gaining  from  an  average  of  87  to  one 
of  124  pounds  in  body  weight,  i.e.,  2.64  therms.  In  Bulletin  283  from 
this  Station  the  average  energy  value  of  a  pound  of  gain  in  empty 
weight  from  87  to  117  pounds  was  found  to  equal  2.58  therms.  Ap- 
parently the  weight  increase  of  sheep  is  remarkably  constant  in  energy 
content,  largely  because  it  is  fairly  constant  in  fat  content.  In  this 
experiment  the  average  fat  content  was  53.6  percent;  in  the  preceding 
experiment  at  this  Station  it  was  found  to  be  47.7  percent,  and  in 
the  experiment  of  Wood  it  averaged  50.7  percent  (on  the  increase  in 
live  weight).  The  crude  protein  percentages  were  not  so  constant, 
averaging  11.9,  13.2,  and  17.6  respectively  for  the  three  experiments. 

Distribution  of  Added  Nutrients  in  the  Carcasses 

It  is  of  interest  to  compute  the  distribution  of  the  added  nutrients 
among  the  dressed  carcass,  the  offal,  and  the  wool.  Such  calculations 
are  complicated  somewhat  by  the  different  methods  of  making  up  the 
samples  for  the  check  and  fat  lambs,  but  satisfactory  results  may  be 
obtained  on  the  assumption  that  the  head  and  feet  bones  possessed 
the  same  chemical  composition  as  the  bones  of  the  dressed  carcass. 

TABLE  32. — PERCENTAGE  DISTRIBUTION  OF  GAINS  IN  CHEMICAL  CONSTITUENTS  OF 
THE  FAT  LAMBS  AMONG  DRESSED  CARCASS,  WOOL,  AND  OFFAL 


Dry 

substance 

Crude 
protein 

Fat 

Ash 

Gross 
energy 

Dressed  carcass.  .  . 
Wool 

66.7 

s  s 

54.8 
26  3 

71.4 
2   1 

15.3 
64  9 

69.6 
5  2 

Offal  

24  .  5 

18.9 

26  o 

19  8 

25  2 

Total  

100.0 

100.0 

100.0 

100.0 

100.0 

The  weights  of  head  and  feet  bones  were  obtained  for  the  fat  lambs, 
so  that  the  composition  of  the  dressed  carcass  can  be  approximated. 
The  results  obtained  on  this  question  are  assembled  in  Table  32. 

'Wood,  T.  B.    Jour.  Min.  Agr.  [Gr.  Brit.]  34,  295.   July,  1927. 


THE  MAINTENANCE  AND  FATTENING  OF  LAMBS  57 

With  the  exception  of  the  added  mineral  matter  the  dressed  car- 
cass received  most  of  the  nutrient  material  added  to  the  bodies  of  the 
lambs  during  their  fattening  period.  An  average  of  66.7  percent  of  the 
added  dry  matter,  54.8  percent  of  the  added  protein,  71.4  percent  of 
the  added  fat,  15.3  percent  of  the  added  mineral  matter,  and  69.6  per- 
cent of  the  added  gross  energy  were  found  in  the  dressed  carcasses  of 
these  lambs.  The  added  wool  contained  about  two-thirds  of  the  added 
mineral  matter  and  about  one-fourth  of  the  added  protein  but  very 
little  of  the  added  energy.  The  mineral  matter  found  in  the  wool  con- 
tained only  a  trace  of  calcium  and  probably  consisted  of  dirt  to  a  large 
extent.  The  failure  of  these  lambs  to  increase  in  calcium  content  altho 
increasing  in  mineral  content  is  thus  partially  explained. 

The  main  difference  in  the  disposition  of  added  nutrients  in  the 
carcass  between  these  young  lambs  and  the  more  mature  sheep  of  the 
preceding  experiment1  relates  to  the  protein.  In  the  former  experiment 
60  percent  of  the  added  protein  was  found  in  the  wool,  the  growth  of 
the  carcass  being  largely  completed.  In  the  present  experiment  less 
than  20  percent  of  the  added  protein  was  found  in  the  wool,  the  dressed 
carcass  alone  containing  about  55  percent  and  the  offal  parts  over 
25  percent. 

With  the  more  mature  sheep,  wool  growth  accounted  for  greater 
percentages  of  all  added  nutrients  than  with  the  growing  lamb.  It  was 
also  formed  at  a  much  more  rapid  rate,  being  equivalent  to  a  daily 
growth  of  .149  pound  of  protein  and  566  calories  of  gross  energy  per 
day  per  1,000  pounds  live  weight.  In  the  experiment  on  growing  lambs 
the  daily  growth  of  wool  contained  an  average  of  only  .086  pound  of 
protein  and  377  calories  per  1.000  pounds  live  weight. 

Utilization  of  Feed  Energy  in  Fattening 

The  relation  between  the  feed  energy  consumed  by  the  fattening 
lambs  and  their  average  daily  retention  of  energy  is  of  interest  in 
throwing  light  upon  the  efficiency  of  utilization  of  energy  by  sheep. 
The  calculations  given  in  Table  33  are  concerned  with  this  relation. 
The  average  energy  content  of  the  lambs  at  slaughter  was  114.8  therms. 
Their  initial  content,  as  computed  from  the  initial  weights  and  the 
average  energy  content  of  the  second  group  of  check  lambs  per  unit 
of  live  weight,  averaged  59.4  therms.  The  gain  in  energy  therefore 
averaged  55.4  therms,  or  568  calories,  daily.  The  average  daily  intake 
of  metabolizable  energy  was  2,427  calories,  of  which  1.254  calories 
were  estimated  to  have  been  used  for  maintenance.  This  estimate  is 
based  upon  the  average  weight  of  the  lambs  during  the  feeding  period 
and  the  average  metabolizable  energy  requirements  for  maintenance 
as  previously  determined,  i.e.,  1,637  calories  per  100  pounds  live  weight. 

'111.  Agr.  Exp.  Sta.  Bui.  283,  243,  Table  25. 


58 


BULLETIN  Xo.  314 


[August, 


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1928]  THE  MAINTENANCE  AND  FATTENING  OF  LAMBS  59 

the  direct  ratio  of  weights  being  used.  Hence,  according  to  these  fig- 
ures 1,173  calories  of  metabolizable  energy  may  be  considered  as  avail- 
able for  production.  The  production  secured  averaged  568  calories 
daily,  or  an  average  of  48.5  percent  of  the  metabolizable  energy  avail- 
able. 

As  previously  mentioned  (page  45),  experimental  work  with  steers 
indicates  a  percentage  availability  of  metabolizable  energy  of  53  to  55 
for  a  ration  of  equal  parts  of  corn  and  alfalfa  hay.  The  results  of  this 
experiment  point,  therefore,  to  a  somewhat  less  efficiency  on  the  part 
of  the  sheep  as  compared  with  the  steer  in  the  utilization  of  metaboliz- 
able energy.  For  alfalfa  hay  alone  results  have  been  reported  previ- 
ously for  sheep  (Bulletin  283)  that  are  equal  to  several  reported  by 
Armsby  for  steers  but  inferior  to  some  of  the  later  results. 


SUMMARY 

The  digestibility  of  a  ration  consisting  of  equal  parts  by  weight 
of  alfalfa  hay  and  shelled  corn  was  investigated  at  two  levels  of  feed- 
ing, one  representing  but  little  more  than  a  maintenance  ration  (eight 
lambs)  and  the  other  representing  full  feed  (five  lambs).  The  coeffi- 
cients of  digestibility  at  the  higher  level  were  generally  greater  than 
those  at  the  lower,  altho  the  differences  were  not  large.  At  the  higher 
level  62.3  percent  of  the  gross  energy  of  the  ration  was  found  to  be 
metabolizable,  while  at  the  lower  only  59.7  percent  was  metabolizable. 
The  metabolizable  energy  of  the  ration  per  kilogram  of  dry  matter  was 
2.794  therms  at  the  higher  level,  and  2.653  therms  at  the  lower.  For 
steers  the  gross  energy  in  a  ration  of  equal  parts  of  corn  and  alfalfa 
hay  has  been  found  to  be  60  to  61  percent  metabolizable. 

In  feeding  tests  upon  eight  lambs  averaging  69  pounds  in  weight, 
the  maintenance  requirements  in  terms  of  pounds  of  feed  and  of 
metabolizable  energy  per  100  pounds  of  weight  have  been  determined 
for  a  ration  containing  equal  parts  of  alfalfa  hay  and  corn.  The  data 
of  feed  consumption,  feed  analyses,  and  digestion  and  metabolism 
trials  have  been  supplemented  by  carcass  analyses  of  check  lambs 
and  of  the  maintenance  lambs  at  the  end  of  their  feeding  period,  in 
order  to  correct  for  a  storage  of  energy  in  the  body.  It  was  found  that 
1.53  pounds  of  feed  and  1,637  calories  of  metabolizable  energy  were 
required  per  100  pounds  weight  for  the  maintenance  of  energy  equi- 
librium. These  values  may  be  compared  with  those  determined  in  a 
previous  experiment  for  a  ration  of  alfalfa  hay  alone,  i.e.,  2.29  pounds 
and  1,820  calories  of  metabolizable  energy. 

Nine  lambs  were  used  in  a  fattening  experiment  to  determine  the 
efficiency  in  the  use  of  metabolizable  energy  for  production.  These 
lambs  were  fattened  from  about  65  pounds  in  weight  to  about  90 


60  BULLETIN  No.  314 

pounds,  at  which  weight  they  were  slaughtered  and  analyzed.  Di- 
gestion and  metabolism  experiments  were  run  upon  five  of  these  lambs. 

Altho  the  daily  rate  of  gain  varied  from  .18  to  .36  pound,  no 
relation  could  be  detected  between  the  rate  of  gain  and  the  composition 
of  the  carcass.  On  the  average  the  fat  content  of  the  empty  carcass 
increased  from  14.15  percent,  as  determined  by  the  analysis  of  eight 
check  lambs  at  approximately  the  initial  weight,  to  24.89  percent. 

The  average  gain  in  empty  weight  was  calculated  to  possess  the 
following  composition:  75.1  percent  of  dry  matter,  11.9  percent  of  pro- 
tein, 53.6  percent  of  fat,  and  2.5  percent  of  ash.  Its  gross  energy  value 
was  2.63  therms  per  pound. 

Altho  the  ash  content  of  the  lambs  increased  during  fattening,  no 
increase  in  the  calcium  content  could  be  demonstrated.  A  small  in- 
crease might  well  have  been  obscured  by  the  possible  error  in  the 
slaughter  experiment.  The  absence  of  any  indication  of  a  large  in- 
crease in  calcium  was  due  to  two  factors.  In  the  first  place,  65  percent 
of  the  increase  in  ash  occurred  in  the  wool,  and  largely  represented 
outside  contamination.  Again,  the  percentage  of  calcium  in  the  ash  of 
the  entire  carcass  decreased  from  27.4  to  28.5  in  the  check  lambs  to 
22.3  in  the  fattened  lambs,  the  maintenance  lambs  showing  an  average 
of  24.4. 

The  gains  in  nutrients  by  the  fat  lambs  were  largely  added  to  the 
dressed  carcass.  Thus  66.7  percent  of  the  dry  matter  of  the  gains, 
54.8  percent  of  the  protein,  71.4  percent  of  the  fat,  and  69.6  percent 
of  the  gross  energy  gained  were  deposited  in  the  dressed  carcass.  The 
wool  growth  accounted  for  8.8  percent  of  the  dry  matter  gained,  26.3 
percent  of  the  protein.  2.1  percent  of  the  fat,  and  5.2  percent  of  the 
energy. 

The  daily  wool  growth  of  these  young  lambs  contained  per  1,000 
pounds  live  weight  .086  pound  of  protein  and  377  calories.  These 
values  are  only  about  60  percent  as  large  as  those  obtained  with  larger 
and  older  sheep  in  a  previous  experiment. 

The  daily  gain  of  energy  by  the  fattening  lambs  averaged  568 
calories.  The  average  intake  of  metabolizable  energy  was  2,427  cal- 
ories daily,  of  which  1,254  calories  were  estimated  to  have  been  re- 
quired for  maintenance.  The  difference,  1,173  calories,  may  therefore 
be  compared  with  the  energy  storage  to  determine  the  efficiency  of 
utilization  of  the  metabolizable  energy  consumed  in  excess  of  the 
maintenance  requirements.  The  daily  storage  of  568  calories  is  48.5 
percent  of  the  metabolizable  energy  apparently  available  for  this  pur- 
pose. We  may  say,  therefore,  that  between  a  maintenance  level  of 
feeding  and  the  full- feed  level  attained  by  the  fattening  lambs,  the 
metabolizable  energy  of  the  ration  of  alfalfa  hay  and  corn  was  48.5 
percent  net  available.  For  steers  a  utilization  of  53  to  55  percent 
would  be  expected  for  this  ration. 


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DIVERSITY  OF  ILUNOIS-URBANA 


